Process for preventing mine explosions



Reiuued Mar. 20, 1928.

v p, Re. 16,914 UNITED STATES PATENT oar-ice.

war/man. TRENT, or NEW YORK, N. in, .ASSIGNOB 'ro TRENT rnocnss oonrom'rrom- NEW YORK, N. Y., A conromrIo or DELAWARE. Y

raocass roa PREVENTING MINE EZPL'OSIOIiIB.

Io Drawing. Original No. 1,642,912, dated September 20, 1927, Serial No. 744,847, flied October 80, 19.

Application for reissue tiled December 14, 1927. Serial No. 240,089.

The invention relates to improvements in a method for preventing dust explosion in dust such as coal mines.

In the operation of mines at the present time it is the practice todistribute inert owdered limestone, shale, silica, soil, or lie like, on the roof ribs and floors of coal mine workings and all places wherever practicable that may offer lodgment for floating coal dust.

This causes dilution of the settled coal dust and retards the exothermic reaction that concentrated coaldust sets u' by oxygen entrainment in the dust and a jacent thereto and by thus retarding the initial heat reactions the coalis less liable to heat up to kindling andexlplosive temperature.

It is impossib e to get a uniform distribution of the dust over the surfaces of the roof,

ribs and floor, inthe-o'rdinary dusting 0 era, tion as about two. thirds of the dustwi 1 get to the floor and one third over'the other surfaces and this ratio should be reversed.

An effort to gets. more uniform distribution has lead to a practice of spreadin adobe mud over these surfaces, but mu both in its wet condition and after drying and wiring, will not permit the coal dust properly to mix with-the same to get the desired dilution.

In the case of neither dust nor mud is the physical character of a coal dust particle changed so as to make it inert orroof against exothermic reaction at ordinary mine working temperatures.

It is an object of the invention to prevent coal dust explosions in mines by coating coal particles with a skin or covering of a hi h ash point viscous oil that will permanent y prevent the particles from setting up low temperature oxidation and then further to safe guard the articles from combustion condi tions by im eddi ng them in a bed or surface of the eavy combustion resistant oil.

In my Patent Number 1,47 9,657 I have disclosed a' process by means of which fine coal is prevented from exploding and also from dusting. I disclose in this patent a process in' which a small percentage of high boiling point oil is mixed with coal dust in an amount sufficient to put a thin film or coat around each particle. This oil coating produces two effects, first it completely re- ,vents the coal particle from generating eat by slow low temperature oxidation or combustion and it prevents the coal particles from dusting, that is, settled under ordinary conditions.

In my Patent No. 1,420,165 I disclose the marked aflinity between 'oil and coal dust and their characteristics to form'a t ue amalgam. Both the filming of the coal particles with oil then embedding or amalgamating these particles in a layer of oil are factors in preventing coal dust explosions.

. The invention primaril consists in applying, to exposed wall sur aces of a mine, or to anysurface that offers lodginent or 001- lectin places for dust, a high boiling point oil w ich is high in flash point and. serves to lodge or entrap particles of coal dust.

it causes it to stay It is contemplated to directthe travel of circulating air that has, or may have at times, suspended coal "particles so as to 've contact with'the oil covered surfaces to' asten and localize the collection of the dust so far asit mayprove practicable in mines.

In additionto dusting. and mudizingf there has'been put. into practice a most hig 1y efl'ective system'desfiribed as ".dust barriers. cifple ofplacing comparatitel'y l'argensnounts o inert dust at strategio,points in rnines,"

the containers beingflelicately positioned so that at any slight atmospheric disturbance This'practice consists in..-'the prin-v the containers will spill the du'stand permit same to become diffused.- in the air or-gases and thus cause the retardation: or suffocation of flame propagation of an explosion at its incipiency. This system may be called a SBCOIIICLHIXQ of'defense and I'wish to acknowledge its .noveltyand its, great usefulness and further to say that the present method de} scribed does not lend itself to this particular practice toprevent or retard an e sion already inaugurated and that it is a system that should be used with the present disclosure for a second line of defense as now used.

Referring now more specificall to my invention I preferably coat the walls and surfaces of a mine wit a hydrocarbon oil having a very high flash point with s'uflicient viscosity to remain on. a surface after having been placed thereon. I may use the residual oil from an oil cracking process, I can use also certain topped oils from which.

, dust sons to contact with the oil comes suitable by 7 dry shale or rock dust so that it will remain diate boiling point fractions. This oil is applied by spraying, painting, or otherwise,

in such places as coal particles are to be found.

The particles of coal suspended in the air contact with the hydrocarbon oil and because of the existing aflinit' between coal and oil are immediately co lected and entra ped and made immune to exothermic reaction below the ordinary combustion temperatures. The oil willaabsorb or collect more than its own weight of coal dust before becomi saturated and inactive and at such times a. ditional oil may be added to the amalgam surface to-restore its. activeness.-

Atplaceswhere dust is collected in rather large tfllantities it will be necessary to remove t e amalgam by scrapin or otherwise and then a plying the new sur aces of oil.

'I. may p ace ventilatingfans in themines to direct theair currents carryi or. I may direct those currents by an other means. The oil to be used is prefera 1y one that contains only fractions that boil at about 300 centigrade and upwards. The ordinary fuel oils of about 12 or 14=9 Baum avity' from which have beenremoved all motions that boil up to 300 c'entigrade are verysuitable. Heavy. transformer oils are likewise suitable and also oils that have the flash point specifications of lubricating oils. Greases of many kinds answer the .pur ose and cheap oil water emulsions such as sediment. are fit for the p ose.

If it is desired to use a .t in oilthathas the other necessary characteristics it bet ickening the same with the coal surfaces having a high entra'p the coal parti them as to of. the oil may be utilized in accordance with this invention.

I claim:

1. A process for preventing mine ex 10- sions consistingin 'ap lying a hydrocar n oil having'a high bOl ing point and a high flash point to a mine surface to entrap and retain finely divided coal particles contacting therewith to rendersaid particles substantially incapable of anexothermic reaction.

2. A recess for preventing mine exglosions w ich consists in applying a by carbon oil having a high i ing oint to a mine surface to entrap coal partic es and to separate them so as to prevent an exothermic .reaction from occurring between said parsurface 0 the mine a high bo1 ing point oil and in brin 'ng the dust particles in con tact with sai 011 surface to coat and agglomerate said dust particles.

,4. A process for preventing mine explosions consistingmin applying a liquid oil iling point to a mine surface and in rejecting-fine coal particles against said oil'coatinlg to enable the oil to es and to so separate revent an exothermic reaction from occurring between said particles.

WALTER TRENT 

